Dripless oils



United t s Patent DRIPLESS OILS Ernest T. Fronczak, Crystal Lake, 111., assignor to The Pure Oil Company, Chicago, 11]., a corporation of Ohio No Drawing. Filed July 29, 1957, Ser. No. 674,632

7 Claims. (Cl. 252-42) This invention relates to new and useful improvements in dripless-oils, and more particularly to improved compositions of dripless-oils containing very low soap concentrations for producing ,a desirable range of viscosity in the oil.

:In certain industrial lubrication applications it is desirable to use a mineral lubricating oil thickened to cause it to remain on various moving parts of machinery without dripping or slinging off. For example, spindles and other components of textile machinery require such lubricants. In formulating lubricants of this type it is possible to use lubricating oils which have inherent high viscosities. However, such oils often'do not have other properties which are desirable in lubricants of this type. There have therefore been developed lubricants, known as dripless-oils, which consist of a mineral lubricating oil base having all of the desired properties except high' viscosity, which base has been thickened to the desired viscosity by addition of a metal soap. The thickening agents 'used are usually soaps that are conventionally employed in preparing greases, and, in fact, the driplessoils are similar to diluted greases, except that oils of specific (normally relatively low) viscosities are used. It has been found, however, that most of the thickening agents used for preparing greases are not satisfactory when used as thickeners for dripless-oils. For'example, the inorganic silica and bentone gelling agents which have proved very satisfactory l tor high-temperature greases are completely unsatisfactory as thickeners for dripless-oils. The amount of these inorganic thickeners required for the production of dripless-oils is uneconomical and these gelling agents are unstable (i.e., settleout) on extended storage. 7 most alkali metal soaps are unsatisfactory thickeners for dripless-oils. These soaps, while producing a fine gelat inous grease structure in greases, produce unstable compositions when diluted to the consistency of a driplessoil, i.e., the soaps tend to agglomerate and precipitate out on extended storage. t

Some commercial dripless-oils, however, have been made using the hydrated calcium soap of tallow as a thickening agent. In making dripless-oils of this type a grease is prepared using a hydrated calcium tallowate in a 300 vis. (SUS at 100 F.) Gulf Coast neutral oil,

followed by dilution of the grease with more of the neutral oil to produce the desired viscosity range .of the resulting oil". These oils, however, posses s'the disadvantage that the soaps may precipitate during'extended storage,- or may be filtered from the oils by the commonly used wick-type feeders. Furthermore, as much as 4% by weight of the soap may be required to achieve the desired viscosity, which in many cases is economically. impractical; It is, therefore, one object of this invention to provide e a m ov .tsqarhi en dl a r ss-o Aluminum, calcium, barium, and

Another object of this invention is to provide an improved dripless-oil which uses a substantially lower concentration of soap thickening-agent than in previous oils.

Another object of this invention is to provide an improved dripless-oil which is easily manufactured and stable on extended storage.

A feature of this invention is the provision of an improved dripless-oil which is thickened by addition of a very small percentage of the sodium soap of the mixed acids which are obtained as the volatile fraction from the vacuum distillation at 200-270 C. and 4-20 mm. pressure of the by-product acids produced in the manufacture of sebacic acid from castor oil by treatment with alkali.

Another feature of this invention is the provision of an improved dripless-oil which consists of a homogenized mixture of a mineral oil base having as its major component a solvent-refined oil, and 0.05-1.0% by weight i of the sodium soap of the volatile by-product acids produced in the manufacture of sebacic acid from castor oil by treatment with alkali.

Other objects and features of this invention will become apparent, from time to time, throughout the specification and claims as hereinafter related.

' fraction from thevacuum distillation at 200-270 C.

, This invention is based upon the discoverey that dripless-oils can be prepared using very low soap concentrations for thickening, when the soap used is an alkali metal soap of the mixed acids which are obtained as the violatile and 4-20 mm. pressure of the by-product acids obtained in the preparation of sebacic acid from castor'oil by treatment with alkali. These soaps, when used in a concentration of ODS-1.0% in a mineral oil base, and

- thoroughly homogenized, produce high-quality driplessoils having a Wide range of viscosities. Dripless-oils containing 0.2-0.7% of these soaps have #4 Ford cup viscosities at 77 R011 30 to 140 seconds. These driplessoils are preferably prepared by first preparing a grease of the lubricating oil base and the soap (astaught in my co-pending patent application, Serial No. 671,141, filed July 11, 1957, entitled Greases) followed by dilution with thelubricating oil'base and homogenization to the desired consistency. In manufacturing dripless-oils of this type,

it is possible to to usesolvent-refined lubricating oils,

invention, the thickening agents used consist of the alkali metal soaps of mixed acids which are by-products from manufacture of sebacic acid from castor oil. These mixedv acids are prepared according to a process described inCheetham et al., U.S. Patent 2,267,269, the process for which will be described more fully hereinafter, and are referred to hereinafter throughout the specification and claims as mixed acids I. Sebacic acid is made commercially by fusing castor oil with caustic alkali, or (as described in U.S. Patent 2,182,056) by heating the two in the presence of water under high pressure. The initial reaction products are octanol-Z, methylhexyl ketone, the sodium salt of sebacic acid, and the sodium salts of various by-product acids formed by side reactions. The

octanol-2 and methylhexyl ketone are removed by dis tillation, and the acids formed by side reactions by dissolving the residue in water and acidifying with a mineral acid to cause the separation into a lower aqueous layer and an upper oily layer. The lower layer is an aqueous I solution of sodium sebacate and is drawn off and acidified V a a a.

. 3 to precipitate the sebacic acid. The upper oily layer contains the by-product acids formed by side reactions. The by-product acids are separated by distillation at low pressures. These acids are subjected to a temperature of about 100-200 C. and 20 mm. pressure for removal of the more volatile acid materials. The mixture is then subjected to progressively increasing temperature between 200 and 270 C. and the pressure gradually reduced from 20 mm. to about 4 mm. At temperatures. between 200 and 270 C. and pressures from 4 to 20 mm. a distillate is obtained which constitutes about 40% of the by-product acids. This distillate consists of a mixture of fatty acids, both saturated and unsaturated, of very uncertain composition which is referred to in the specification and claims as mixed acids 1. Mixed acids I consist of a very complex mixture of fatty acids con taining from 11 to 18 carbon atoms per molecule, including both saturated and unsaturated acids. Among the unsaturated acids, there are some with cis configurations and some with trans configurations. The exact analysis of the composition has never been completely worked out and it has never been reproduced by a syn.- thetic mixture of fatty acids because of its complexity and because of the somewhat unique combination of titre, acid value and iodine value. Mixed acids I contain about 15% C1143 acids, about 25% C1445 acids and about 60% C1648 acids. These mixed acids have the following properties:

Titre C-..

Iodine value 36-42 Fatty acid (calculated as percent oleic) 112-115 Acid value 220-256 Saponification value 221-227 NPA color 1 /2 Percent Mixed acids I 3-20 Alkali metal hydroxide 0.75-5.0 Solvent-extract from production of high V.I.

bright stock 6-12 Solvent-refined 200 vis. neutral oil 65-85 Coupling agent (glycerol, ethyleneglycol, or a liquid polyethyleneglycol) 0.3-6.0

Mixed acids I are as previously defined. The metal hydroxide may be of any alkali metal such as lithium, potassium or sodium, but is preferably sodium hydroxide.

. In this grease composition any suitable bright stock extract or neutral oil may be used, dependent only upon the economic factors in making the grease and the ultimate composition of the dripless-oil desired. A satisfactory grease (and dripless-oil) may also be prepared using so1 vent-refined oils without any solvent extract, or using distilled lubricating oils.

In preparing the grease base from the above ingredients, the acids, coupling agent, bright stock extract, and about 20% of the solvent-refined neutral oil are charged to a grease-making kettle and heated to about 160- 170 F., with agitation. The metal hydroxide is then added, as a 40% aqueous solution, and the temperature of the batch slowly increased to 320-340 F. During the increase in temperature the acids are completely neutralized and at the maximum temperature the batch is completely dehydrated after about 1 hour. The dehydrated mixture of oil and soap is then mixed with the remainder of the neutral oil to the desired soap concentration, which reduces the batch temperature to about 200 F. This base:

grease mixture is then homogenized in a colloid mill to produce a fine-textured fiber grease.

In preparing a dripless-oil, the grease base prepared according to the above procedure is diluted with a selected mineral lubricating oil to a soap concentration having the desired viscosity range. The mineral oil used to dilute the grease is preferably a blend of solvent extract from the preparation of high V.i. bright stock and solvent-refined 200 vis. neutral oil, having a viscosity of about 300 SUS at F., or may be a 300 vis. (SUS at 100 F.) Gulf Coast neutral oil. The blend of bright stock and solvent-refined neutral is preferred in this composition because these oils are cheaper and more readily available.

In the preparation of dripless-oils according to this invention, the bright stock extract (which represents about 10% of the total diluent oil) is charged to an open-top grease kettle and heated to -160 F., with agitation. The grease base is then charged to the kettle and the temperature increased to about -200 F., with continued agitation. Agitation is continued until the dispersion of grease in the solvent-extract is uniform. The batch is then slowly cut back, or diluted, with the 200 vis. neutral oil, with continued agitation at about 190 F. Agitation of the mixture is continued for about 15 minutes after all of the oil has ben charged to the kettle. At this point the concentration of soap in the oil is in the range of 0.05-1.0%, depending upon the desired viscosity of the product. The dilute batch is then circulated through a colloid mill and completely homogenized for a period of about 30 minutes to 2 hours. During this homogenization the viscosity of the oil increases by about 10 to 50% and a stable mixture is produced from which there is no precipitation of soap even after centrifuging for 1 hour at 1000 r.p.rn. In this process, the final step of homogenizing the diluted oil mixture is absolutely necessary to produce a stable product of the proper viscosity.

The utility and superior properties of dripless-oils produced according to this invention are illustrated by the following examples, which, however, should not be considered as limiting the dripless-oil compositions to those specifically described.

EXAMPLE 1 In preparation for producing a dripless-oil according to this invention, a grease was prepared by the abovedescribed procedure from the following ingredients in the proportions indicated:

Proportion Component (wt.

percent) Mixed acids T 9 Sodium hydroxide. 1.8 Bright stock extract 8.9 200 vis. neutral oil 79. 4 Glycerol. 0. 9

(1) The bright stock extract used is a highly aromatic oil of high viscosity. It is obtained as the phenol extract from the production of solvent-refined, high V.I. bright stock and has the following physical, and chemical properties:

(2) The neutral oil used was a200 vis. (SUS at 100 F.) solvent-refined neutral oil having the following An open-top grease kettle was charged with 16.65 pounds of the bright stock used in the grease formulation,

and heated to 150-160 F. with agitation. To this oil there was added 16.65 pounds of the grease obtained from the above procedure. The mixture of grease and oil was agitated and heated to about 190 to 200 F. for about 1 hour until a uniform dispersion was obtained. The batch was then cut back with 149.87 pounds of the 200 vis. neutral oil used in preparing the grease, while maintaining the temperature at about 190 F. After all of the oil was charged to the kettle, agitation was continued for about minutes. The batch was then circulated through a colloid mill (a Marco Kom-Bi-Nator) for 30 minutes, while continuing to agitate the portion of the batch returned to the kettle below the surface of the oil. A sample of this oil was cooled to 77 F. and its viscosity measured using a #4 Ford cup, the viscosity being about 75 seconds.

EXAMPLE 2 In order to compare the dripless-oils of this invention with those produced by other commercial methods, a number of dripless-oils were prepared and compared with commercial products for the range of soap concentration required to produce various grades of oils. For conven ience, dripless-oils of various consistencies may be grouped into four grades, according to. Ford cup viscosities. These grades are defined by a viscosity range which is measured as the number of seconds required for 60 cc. of sample oil to flow through a #4 Ford cup viscosimeter at 77 F. In this grading system, grade A represents a viscosity range of 75-140 seconds, grade B represents 55-75 seconds, grade C represents 40-55 seconds, and grade D represents 30-40 seconds.

A series of commercial-type dripless-oils was prepared using calcium tallowate as the thickening agent. In making these oils, soap concentrate approximating an N.L.G.I. No. 2 grease. was first prepared by saponifying tallow with calcium hydroxide under pressure and dehydrating the same, cutting back the soap dispersion to about 10% soap concentration with the desired oil, and rehydrating the soap. The grease concentrate was then diluted with additional oil, using heat, agitation, and homogenization, to obtain the soap concentration and consistency necessary for the specified grade of driplessoil. These oils are made and sold commercially but are subject to the disadvantage that the soaps tend to precipitate during storage, or during feeding through a wick feeder, and use a relatively high soap concentration.

Dripless-oils of the commercial type were prepared as just described, and also dripless-oils according to this invention, as in Example 1, of different soap concentrations in order to determine the concentration of soap in the oil required for the viscosity range of various grades of dripless-oils. The range of soap concentration required for the various grade oils is set forth in Table I.

Table 1" I nr'i PL'Ess oiLs "IHICKENED WITH SOAP I V Soap Concentration Percent Grade Viscosity Percent Sodium Range 1 Calcium Seat of Tallowate Mixed in Oil Acids I Base 9 in Oil Base 8 fining, as used in the formulation oi the grease, which has a viscosity of about 300 SUS at F.

In the preparation of dripless-oils according to this invention each grade of oil may be made by cutting back the original grease base to the specific grade desired, or may be made by cutting back a heavier (more viscous) of oil previously prepared. However, it is essential that each blend be thoroughly homogenized after cut back. From the foregoing tabular data, it is seen that the oils produced according to this invention are more satisfactory oils, and use much smaller amounts of soap than driplessoils previously prepared. As indicated in Example I, these oils are stable against settling of the soap during storage as shown by the fact that no soap settled out after one hour of centrifuging at 1000 r.p.m. The very low soap concentration also permits the use of these oils with wick-type feeders which tend to filter soap from oils having higher soap concentrations.

While this invention has been described with particular emphasis on the use of the sodium soaps of mixed acids I for thickening blends of solvent-refined neutral oils and bright stock extract, it is to be understood that these soaps function equally well in thickening solvent-refined oils alone, and for distilled lubricating oils, or blends thereof. These oils may also be prepared using other alkali metal soaps, such as potassium or lithium soaps of mixed acids I, utilizing the same procedures used for the preparation of the sodium soaps.

Having thus fully and completely described my invention, and several specific examples of the best mode of carrying out said invention, it should be understood that within the scope of the appended claims this invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A dripless-oil consisting essentially of a homogenized mixture of a mineral oil base and 0.05-1.0% by weight of an alkali metal soap of mixed acids I, said mixed acids I comprising the volatile fraction from the vacuum distillation at 200-270 C. and 4-20 mm. pressure of the by-product acids obtained in the preparation of sebacic acid from caster oil by treatment with alkali.

2. A dripless-oil according to claim 1 in which the mineral oil base consists of a 300 vis. (SUS at 100 F.) oil.

3. A dripless-oil according to-claim 1 in which the mineral oil base consists of a mixture of a 200 vis. solventrefined neutral oil and an aromatic oil consisting of a solvent-extract from the solvent-refining of high V.I. bright stock, blended to a viscosity of about 300 SUS at 100 F.

4. A dripless-oil according to claim 1 having a soap concentration of 0.2-0.7% and a #4 Ford cup viscosity at 77 F. of 30-140 seconds.

5. A method of preparing a dripless-oil by dilution with mineral oil of a grease consisting essentially of a g mineral oil base, a coupling agent of the group consisting of glycerol, ethylene glycol, and liquid polyethylene glyeols, and 3-20% by weight of the sodium soap of mixed acids I, said mixed acids I comprising the volatile fraction from the vacuum distillation at 200-270 C. and 4-20 mm. pressure of the by-product acids obtained in the preparation of sebacic acid from castor oil by treatment with alkali, which comprises charging the grease and a small portion of the diluent mineral oil to a processing vessel at 150-160 F., agitating the mixture and increasing the temperature gradually to 190200 F. until the dispersion is uniform, diluting the mixture with the balance of the mineral oil diluent at l90 F; to produce an oil containing 0.05-1.0% by weight of soap, and homogenizing the mixture for a time sufficient to produce a stable oil of the desired viscosity.

6. A method according to claim 5 in which the initial portion of the diluent oil is an aromatic oil obtained as a solvent extract in the production of high V.I. bright stock and the remainder of the diluent oil is 200 vis. 20-

solvent-refined neutral oil.

8 7. A method according to claim 6 in which the solventextract is about 10% of the total diluent oil, the neutral oil is about 90% of the total diluent oil, the grease has an initial concentration of 9% of soap, and is diluted to a concentration of 0.2-0.7% soap to produce an oil having a #4 Ford cup viscosity of 30-140 seconds at References Cited in the file of this patent UNITED STATES PATENTS 2,182,056 Brusonet al. Dec. 5, 1939 2,538,280 OFHalloran et al. Mar. 4, 1952 OTHER REFERENCES 

1. A DRIPLESS-OIL CONSISTING ESSENTIALLY OF A HOMOGENIZED MIXTURE OF A MINERAL OIL BASE AND 0.05-1.0% BY WEIGHT OF AN ALKALI METAL SOAP OF MIXED ACIDS I, SAID MIXED ACIDS I COMPRISING THE VOLATILE FRACTION FROM THE VACUUM DISTILLATION AT 200*-270*C. AND 4-20 MM. PRESSURE OF THE BY-PRODUCT ACIDS OBTAINED IN THE PREPARATION OF SEBACIC ACID FROM CASTER OIL BY TREATMENT WITH ALKALI. 